//
// Created by zhangrongxiang on 2017/10/12 16:02
// File server
//

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>

#define BUFSIZE 1024

int main(int argc, char *argv[]) {
    int server_sockfd;
    int len;
    struct sockaddr_in my_addr;   //服务器网络地址结构体
    struct sockaddr_in remote_addr; //客户端网络地址结构体
    int sin_size;
    char buf[BUFSIZE];  //数据传送的缓冲区
    memset(&my_addr, 0, sizeof(my_addr)); //数据初始化--清零
    my_addr.sin_family = AF_INET; //设置为IP通信
    my_addr.sin_addr.s_addr = INADDR_ANY;//服务器IP地址--允许连接到所有本地地址上
    my_addr.sin_port = htons(8000); //服务器端口号

    /*创建服务器端套接字--IPv4协议，面向无连接通信，UDP协议*/
    if ((server_sockfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
        perror("socket");
        return 1;
    }

    /*将套接字绑定到服务器的网络地址上*/
    if (bind(server_sockfd, (struct sockaddr *) &my_addr, sizeof(struct sockaddr)) < 0) {
        perror("bind");
        return 1;
    }
    sin_size = sizeof(struct sockaddr_in);
    printf("waiting for a packet...\n");

    /*接收客户端的数据并将其发送给客户端--recvfrom是无连接的*/
    if ((len = recvfrom(server_sockfd, buf, BUFSIZE, 0, (struct sockaddr *) &remote_addr, &sin_size)) < 0) {
        perror("recvfrom");
        return 1;
    }
    printf("received packet from %s:\n", inet_ntoa(remote_addr.sin_addr));
    buf[len] = '\0';
    printf("contents: %s\n", buf);
    close(server_sockfd);
    return 0;
}